1. Field of the Invention
This invention relates to a wear and acid resistant paste which is used for forming a thick electrically conductive film.
2. Description of the Prior Art
A household electric appliance usually has a number of control knobs which may be turned, pushed or pulled to switch on or off the power supply, turn up or down the volume or output, or otherwise control the operation of the appliance. The appliance has a plurality of openings through which shafts extend from the knobs to various parts in the appliance. These openings are likely to cause a serious problem particularly to a cooking utensil. It is impossible to prevent effectively the leakage of water, oil, etc. into the utensil through those openings which is very likely to result in its failure or erroneous operation.
The presence of those openings does not permit the washing of the appliance even if it becomes dirty. Therefore, a flat control panel requiring no such opening, and known as a touch panel has come to be used for an electric cooking utensil, too.
While various types of touch panels are known, the commonest type comprises a glass substrate, and electrodes and circuits formed on its surface from a transparent electrically conductive film of a material such as tin or indium oxide. This film has, however, the disadvantage of getting gradually worn if an acidic cleansing agent containing polishing sand is rubbed thereagainst. The touch panel on a cooking utensil is usually exposed to oil, soup, etc. scattering from a cooking pan. Therefore, there has been a strong desire for the development of a material which is used to form a conductive film defining a touch panel, and which withstands washing or cleansing.